Abstract
In this work, we suggest a modified phase-field model for simulating the evolution of mixed mode fractures and compressive driven fractures in porous artificial rocks and Neapolitan Fine Grained Tuff. The numerical model has been calibrated using experimental observations of rock samples with a single saw cut under uniaxial plane strain compression. For the purpose of validation, results from the numerical model are compared to Meuwissen samples with different angles of rock bridge inclination subjected to uni-axial compression. The simulated results are compared to experimental data, both qualitatively and quantitatively. It is shown that the proposed model is able to capture the emergence of shear cracks between the notches observed in the Neapolitan Fine Grained Tuff samples as well as the propagation pattern of cracks driven by compressive stresses observed in the artificial rock samples. Additionally, the typical types of complex crack patterns observed in experimental tests are successfully reproduced, as well as the critical loads.
Highlights
The ability to predict rock behaviour using numerical models is pivotal to solve many rock-engineering problems
The phase-field approach is based on the variational formulation for quasi-static brittle fracture mechanics first introduced by Francfort and Marigo (1998) and further developed by Bourdin (2007), who first introduced a numerical implementation of the regularised approximation of the variational formulation
In this work we have presented a modified phase-field fracture model for simulation of crack propagation in porous rocks
Summary
The ability to predict rock behaviour using numerical models is pivotal to solve many rock-engineering problems. Tanné et al (2018) demonstrate the capability of the phase-field model to predict crack nucleation for Mode I cracks for geometries without any singularities in the stress field These contributions assume that the critical energy release rate for different fracture modes are equal, which is not the case for rock and rock-like materials, see, e.g. The critical release rate for tensile cracks can be orders of magnitude smaller than the critical energy release rate for shear cracks and compressive stresses can lead to the formation of compaction driven cracks To capture these characteristic behaviours, we follow the work of. To demonstrate the capability of the proposed model to predict nucleation of fractures for notched specimens, we compare the numerical results to digital image correlation (DIC) of experiments performed on rock specimens subjected to uniaxial plane strain compression (Nguyen 2011).
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